In general, elevators have an elevator car which is movable in an elevator shaft. If the capacity of the elevator to be increased and thus the performance of the elevator to be enhanced, generally several elevator shafts are combined adjacent to each other in an elevator system. Apart from such a modular extension for increasing the capacity, there is an approach of operating several elevator cars in a single elevator shaft so as to further increase the performance of the elevator system. In order to avoid a mutual interference of the individual elevator cars within a commonly used elevator shaft, the elevator cars can be moved in a uniform direction in the respective elevator shaft in the same manner as in a paternoster, for example. However, in this case a respective separate shaft for the upwardly moving and the downwardly moving elevator cars has to be provided. Furthermore, there is a need of a device for transporting the individual elevator cars from the one elevator shaft or shaft to the other.
Other elevator systems use several shafts in which a number of elevator cars can be independently moved both upwards and downwards in the same respective shaft. At the upper and lower ends of the shafts, elevator cars are displaced from the one shaft to the adjacent shaft on demand so as to be able to provide the respective elevator car to the passengers according to demand and utilization.
If, for example, in a first shaft a first elevator car moves upwards within a particular section and a second elevator car is simultaneously demanded in this section for a downward movement, the second elevator car cannot be used in the first shaft in the opposite direction to the upward moving first elevator car. The second elevator car is thus transported, by means of a device for displacing elevator cars between the elevator shafts, between the first shaft to a second elevator shaft in which there are no elevator cars or at least only elevator cars which are not on a collision course in the respective section.
With such an exchange or displacement of the individual elevator cars to adjacent elevator shafts, the entire elevator system is very flexible and can flexibly and efficiently react to corresponding demands and thus increase the performance of the elevator system.
Another application range for devices for displacing elevator cars to other elevator shafts is illustrated in the patent document U.S. Pat. No. 5,799,755. Herein, an elevator car can be moved between two elevator shafts for providing an elevator system for large buildings or large lifting heights. In this case, an elevator car is translated on rollers in an elevator frame within a first shaft. At the end of the first shaft, the elevator car is rolled out of the frame and displaced to a rollable platform. The elevator car is then rolled from the rollable platform to another elevator frame which transports the elevator car further upwards in a second elevator shaft. However, in the illustrated elevator system, several elevator cars cannot be operated within the same elevator shaft.